1. Field of the Invention
The present invention relates to a high dense sintered body of aluminum nitride, a method for preparing the same and a member for manufacturing semiconductor using the sintered body.
2. Description of the Prior Art
Materials mainly composed of aluminum nitride (AlN) have good thermal conductivity and insulating property so that they have been usually used for electrostatic chucks fixing wafers during semiconductor manufacturing process or for heaters which heat wafers during fixing in CVD process and the like.
The electrostatic chucks fix wafers using an electrostatic force and can be classified to a Johnsen-Rahbek type and a coulomb type according to their adsorbing way.
The Johnsen-Rahbek type electrostatic chuck generally has low volume resistivity of about 1×109˜1×1012 Ωcm so that electric charges come to be charged on a dielectric adsorptive surface for wafer due to such low volume resistivity. The electrostatic attraction between the electric charges of the surface makes the wafer to be fixed.
Since the conventional AlN materials have low volume resistivity as well as low relative density, they were mainly used for the Johnsen-Rahbek type electrostatic chucks having low volume resistivity.
The Johnsen-Rahbek type electrostatic chucks, however, have problem that the leakage current thereof is large and a wafer is hardly detached from the electrostatic chucks due to the remained electric charges on the surface of the electrostatic chucks even after interrupting the application of direct voltage.
Meanwhile, the coulomb type electrostatic chucks fix wafers using an electrostatic attraction between the differently charged particles present on the upper/lower surfaces of a dielectric. Said coulomb type electrostatic chucks show low leakage current and good detachment property at the volume resistivity of 1×1015 Ωcm or more.
Therefore, aluminum nitride materials which can be applied to even a member for manufacturing semiconductor requiring high volume resistivity like the coulomb type electrostatic chucks as well as the Johnsen-Rahbek type electrostatic chucks have been needed.